Abstract
The cantilever beam configuration plays an important role in the power extracted from the vibration-based piezoelectric energy harvesters. Although it has already been proven that triangular and trapezoidal shapes optimize and improve the electrical output of the piezoelectric energy harvesters, the impact of other shapes has not been considered. It is necessary to figure out which shape can provide the maximum amount of power and efficiency, as well. In this article, a complete study regarding the influence of non-uniform theories using both Timoshenko and Euler–Bernoulli beams for both unimorph and bimorph states is carried out. The width and height of the cantilever beams are changed based on the degree of the polynomial function. To solve the equations, finite element method with the application of two different elements including 4-degree-of-freedom model and 8-degree-of-freedom model is adopted. Based on the analysis, it can be concluded that by increasing the degree of non-uniformity and slenderness ratio, the amount of harvested electrical output rises. Moreover, the difference between two beam theories is significant for thick beams with small slenderness ratios. In addition, the effects of non-uniformity including the tapering ratio described by polynomial functions on the efficiency of piezoelectric energy harvesters are studied.
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